Photographic color development with pyrazoline developers



United States Patent PHOTOGRAPHIC COLOR DEVELOPMENT PYRAZOLINE DEVELOPERS Ottmar Wahl, Opladen, Rudolf Mersch, Leverkusen- Bayerwerk, and Walter Piiscli'el, Dusseldorfi-G'ermany, assiguors to AGFA Aktiengesellschaft, Leverkilsen, Germany, a corporation of Germany No Drawing. Application July 7, 1955 Serial No. 520,608

Claims priority, application Germany July 8, 195 1 2 Claims. (CI. 96-55) The present invention relates to a process for the production of photographic color images by color development and more especially to such processes in which 1-(4'-aminophenyl)-3-amino-pyrazolines are used as color forming developing substances.

In the production of colored images by color forming development of exposed silver halide emulsion layers, a colored image is formed in addition to the silver image by the oxidation product of the developer reacting with color couplers which are present at the same time, thereby forming a dye. Particular practical importance has formerly been assumed by those processes in which p-phenylene diamine or its derivatives have been used as developer. p-Aminophenol and its derivatives have also been described for this purpose.

It has now been found that novel effects such as were not possible with the hitherto known developers may be produced with 1-(p-arninophenyl)3-aminopyrazoline and its derivatives in the color development of exposed silver halide emulsions. The derivatives of l-(p-an'iinophenyl)-3-aminopyrazoline are obtained by substitution of the hydrogen atoms in the l-phenyl nucleus and in the heterocyclic ring, and as 's'iibstitiidiit's, there "are mentioned, by way of example, alkyl, aryl, aralkyl, acyl, alkoxy, carboxy, amino, hydroxyl, halogen and sulpho groups. Examples of such compounds are: 1-(4'-amino- 3' methoxyphenyl) 3 aminopyrazoline dihydrochloride, 1 (4 amino 3 methylphenyl) 3 aminopyrazolinedihydrochloride, 1 -(4" aminophenyl 2- hydrochloride, 1-(4-amino- I V I inopyrazolinedihydrochloride, (4- amino- 3' ca'rboxyethylphenyl) 3 aminomthyld aminopyrazolin iiyrgfzolinediliydrochldride.

Whereas, for. example, 1-(p-aminophenyl)-4-aminopyrazolones have not been found suitable -for effective color-developingthe compounds according to the present shades {of the dyestufis 'which are obtained' by the couh pling oi the development products of these compounds with color couplers in color development are very different as compared with those which are obtained with the knciwn p-phenylene diamines. As will be seen from the following Example 1, the absorption maximum of "the "dyestuffs "obtained is displaced by up to 100 rm "to- 2,892,714 Patented June 30, 1959 Ice wards longer wave length. In addition essential differences are shown in other properties or the dyestuffs as compared with the corresponding dyestuffs obtained with the known color developers, for example, as regards increased resistance to acid. Owing to the increased developing and coupling intensity, it is possible to obtain additional advantages as regards the sensitivity of the material for color photography.

l-(p-aminophenyl)-3-aminopyrazoline may be obtained by 1-(p-acylaminophenyl)-3-aminopyrazolines, such as, for example, the acetyl derivative, being subjected to alkali saponification. The derivatives of this compound may be prepared in analogous manner (see in this connection application relating to Process for the production of l-(p-a'rninophenyl)-3-aminopyrazoline Serial No. 515,558 filed June 14, 1955, by Rudolf Mersch and D'e'tlef Delfs, now U. S. Patent 2,840,567, granted June 24, 1958, and assigned to the assignee of the present application. Furthermore there may be applied the process disclosed in the copending application Serial No. 440,562, filed June 30, 1952 and now abandoned. Example 7 of that application discloses that the above acetyl den'vative is made by introducing one mol of N-nitroso- N-'(p'-'acetaminophenyl)-beta amino propionitrile and 200 grams of zinc dust into 2 liters of 10% acetic acid, after the reductionis complete filtering OK the zinc slurry with suction, washing with hot acetic acid and supersaturating the filtrate with acetic acid. The l-(p-acetyl amino phenyl)-3-aminopyrazoline precipitates out in good yield and hasa'i'rieltingpoint of 204 C.

Example 1 An exposed photographic silver halide emulsion, in which is incorporated l-(4-sulphophenyl)-3palmity1- pyrazolone(5) as color coupler, was developed in a developer solution of the following composition at 18 to a gamma equal to 0.7

l-(p-aminoph enyl)-3-aminopyrazoline chloride g.. 0.9

Potassium carbonate ..g Potassium bromide g 2 Sodium sulphite g 3 Water litre 1 The required .gamma was reached after a development A period of 7 minutes at 18 was necessary in this developer to reach a gamma equal to 0.7.

The following table shows the color displacement produced according to the invention as compared with the color development with 4-amino-ethyl-hydroxyethyl ania line,'using difierent color couplers:

Example 2 An exposed photographic silver halide emulsion having incorporated 1-(4-sulphophenyl)-3-palmityl-pyrazolone() as color coupler, was developed in a developer solution of the following composition to a gamma of 0.7:

l-(4'-amino-3'-methoxy phenyl)-3-amino pyrazolinedihydrochloride g 0.7 Potassium carbonate 70 Potassium bromide Q 2 Sodium sulphite g 3 Water es- 1 The desired gamma was obtained after a development time of 3 minutes; the relative sensitivity was to 2.5.

Example 3 1-(4-amino-3'-chloro-phenyl)-3-amino pyrazoline dihydrochloride 3 1.5 Potassium carbonate g 70 Potassium bromide g 2 Sodium sulphite g 3 Water es..- 1

The desired gamma was obtained after a development time of 4 minutes; the relative sensitivity was 2.0.

Example 4 An exposed photographic silver halide emulsion having incorporated 5-(4'-stearoyl amino benzoyl aceton)- aminoisophthalic acid as color coupler, was developed in a developer solution of the following composition to a gamma of 0.7:

1-(4'-amino-3'-methyl phenyl)-3-amino pyrazoline dihydrochloride g 0.9 Potassium carbonate 70 Potassium bromide Q 2 Sodium sulphite g 3 Water es" 1 The desired gamma was obtained after a development time of 3 minutes; the relative sensitivity was 2.5.

Example 5 1-(4'-amino-2-methyl phenyD-3-amino pyrazolinedihydrochloride g 1.2 Potassium carbonate g 70 Potassium bromide E 2 Sodium sulphite "g-.. 3 Water litres..- 1

The desired gamma was obtained after a development time of 3 minutes; the relative sensitivity was 2.0.

Example 6 An exposed photographic silver halide emulsion having incorporated 1-(4'-sulphophenyl)-3-palmityl-pyrazolone(5) as color coupler was developed in a developer solution of the following composition to a gamma of 0.7:

1 (4-amino-3'-methoxy phenyl)-3-aminopyrazoline dihydrochloride g 0.7 Sodium carbonate g 50 Potassium bromide Q 2 Sodium sulphite g 3 Water litres-.. 1

The desired gamma was obtained after a development time of 4 minutes; the relative sensitivity was 2.5.

Example 7 An exposed photographic silver halide emulsion having incorporated 1-hydroxy-4-sulfo-2-naphthoic acid stearyl anilide as color coupler was developed in a tie veloper solution of the following composition to a gamma of 0.7:

1-(4-amino-3-chloro phenyD-S-amino pyrazoline di- The desired gamma was obtained after a development time of 5 minutes; the relative sensitivity Was 2.5.

The 1-(4'-aminophenyl)-3-amino-pyrazoline is produced by refluxing 21.8 grams of l-(p-acetoarninophenyl)-3-aminopyrazoline (M.P. 204 C.) with 220 ml. of 5% aqueous sodium hydroxide solution for 6 hours and thereafter cooling the reaction mass. The crystals obtained melt at about C. with decomposition. The l-(p-acetoaminophenyl)-3-aminopyrazoline is prepared in accordance with the disclosure contained in Example 14 of British Patent No. 679,678.

The two further pyrazolines referred to above are produced in analogous manner.

What we claim is:

l. A process for the production of colored photo graphic images which comprises providing a photographic silver halide emulsion with a latent image and developing this image with an alkaline aqueous solution of a developer which is essentially a compound of the formula:

in which R stands for a member .of the group consisting of hydrogen, alkyl, alkoxy and halogen, this development being carried out in the presence of a color coupler capable of reacting with the oxidation product of said compound to form a dye.

2. A process according to claim 1 wherein the developer compound is 1-(4'-aminophenyl)-3-amino pyrazoline.

References Cited in the file of this patent UNITED STATES PATENTS 2,533,514 Sawdey et a1 Dec. 12, 1950 

1. A PROCESS FOR THE PRODUCTION OF COLORED PHOTOGRAPHIC IMAGES WHICH COMPRISES PROVIDING A PHOTOGRAPHIC SILVER HALIDE EMULSION WITH A LATENT IMAGE AND DEVELOPING THIS IMAGE WITH AN ALKALINE AQUEOUS SOLUTION OF A DEVELOPER WHICH IS ESSENTIALLY A COMPOUND OF THE FORMULA 